Increased computing capacity and speed made possible by new powerful microprocessors has resulted in a plethora of portable electronic devices, such as hand-held video games, laptop computers, and pen-based computers. Pen-based computers are now used in a variety of situations ranging from inventory record keeping to patient assessment in hospitals. The primary output device and, in the case of pen-based systems, for input as well, is the screen display. Touch panels of pen-based systems and displays of notebook computers which are glass are quite fragile, and can be severely damaged when the device is dropped from a relatively short distance, even from a height of less than three feet. Further, the electronic components themselves may also be subject to damage from mechanical shock. The fragile nature of these display screens and associated electronics may limit the use of portable electronic devices in environments where a high degree of durability and ruggedness is required.
Such devices are customarily protected by enclosing the components in an impact resistant plastic case. A typical case used to enclose a pen-based computer is composed of one or more high-impact plastics, such as polycarbonate and ABS. This type of case is strong enough to withstand a drop onto a non-yielding surface. However, while the plastic case may survive, the resulting impact forces transferred to internal components can be severe enough to damage internal electronic components, such as disc drives and display portions. A glass screen, particularly of a larger size included in a pen-based computer or portable work slate unit, is particularly susceptible to damage in this manner.
While devices could be fitted with an external armor to absorb mechanical shock or impact, surrounding the device with such impact resistant armor inherently increases the size and weight of the unit and thus negates much of the advantages of portability. Various other forms of shock protection such as gaskets, springs and rubber mounts are used in other applications for purposes of shock or vibration isolation. However, such prior arrangements are typically inadequate for present purposes for one or more of the following reasons. Three-dimensional protection is not provided so as to be responsive to impacts incident in any possible direction; one or two-dimensional protection may be provided. The mounting arrangement is not sufficiently robust to maintain positional integrity of components following a drop from a significant height onto a concrete surface. Only vibration isolation may be provided, without significant shock absorption on substantial impact. Springs or other compound type materials may be employed which do not possess shock damping or absorption properties. Such inadequacies have resulted in the absence of a suitable solution applicable to drop protection of portable electronic units, particularly those including displays of significant size.
It is therefore an object of the present invention to provide shock resistant portable electronic units characterized by one or more of the following:
The display and associated electronics of the unit are supported by an internal frame unit mechanically isolated from a shock resistant enclosure.
The display and associated electronics of the unit are three-dimensionally cushioned by resilient damping material.
The unit includes a shock damping configuration robust enough to maintain component positional integrity after the unit is dropped with any direction of impact.
The unit includes a shock damping configuration which is inexpensive and readily assembled.
The shock damping configuration provides a three-dimensional multi-point damping system utilizing thermoplastic elastomers for shock damping cushioning.